1. Field of the Invention
The present invention pertains to sound pressure level meters. In particular, the present invention pertains to a temporarily mountable automotive sound pressure level meter for use in measuring and comparing measured sound pressure level readings.
2. Description of the Related Art
Sound pressure level (SPL) meters are devices used to measure the magnitude of acoustic energy, or sound. Typically SPL meters generate a measure, or SPL reading, of sound in decibels. Conventional SPL meters can be used to measure a variety of acoustic events. For example, an airport authority may use an SPL meter to measure the decibel levels reached in neighborhoods surrounding an airport during the take-off/landing of commercial aircraft; a factory manager may use an SPL meter to assure that decibel levels on a plant floor are within government mandated safety limits; or an acoustics engineer may use an SPL meter to assess the propagation of sound within a theater or amphitheater. Further, SPL meters are commonly operated at drag-car races to measure the sound pressure levels generated by high performance dragsters during competition or to measure the sound pressure levels generated by a cheering crowd in a stadium. In recent years, due to the growing popularity of high performance automobile audio systems, SPL meters are also commonly used to conduct automobile audio system SPL competitions. When used to conduct an SPL competition, an SPL meter is used to measure a maximum SPL reading from each of the respective competitors. Competition officials typically observe the maximum SPL reading produced and manually identify a new maximum reading. The competitor whose vehicle achieves the highest SPL reading is declared the winner.
Unfortunately, many conventional SPL meters are not well suited for supporting automotive audio system SPL competitions. For example, to conduct a fair automotive audio system SPL competition, SPL meters not only have to be consistently accurate, they must be capable of being mounted within the respective competing vehicles in a consistent manner. One conventional SPL meter typically used in automotive audio SPL competition includes an SPL meter chassis and an external microphone that is connected to the SPL meter chassis via a cable. Other conventional SPL meters include microphones that protrude significantly from the SPL meter body. Such conventional SPL meters are not easily mountable within an automobile due to the presence of the external microphone cable or protruding microphone, respectively.
SPL meters are typically sensitive pieces of electronic equipment that are easily damaged by rough handling and severe operating environments. Such characteristics greatly diminish the suitability of many conventional SPL meters for use in automotive audio SPL competitions and/or for prolonged use in monitoring SPL levels in individual vehicles due to the environment extremes that are typically experienced by vehicle interiors and the constant handling of the SPL meter as the meter is moved from vehicle to vehicle in SPL competitions. Further temperature and humidity extremes can affect the accuracy of conventional SPL meters that have not been hardened for use under such conditions.
Another drawback to conventional SPL meters is their overall complexity due to capabilities and features that are not needed for SPL vehicle competitions and/or for monitoring sound pressure levels in a personal vehicle. Such complexity typically manifests itself in an overly complex set of optional parameters, an overly complex set of operating procedures, and/or an overly complex output display that is difficult to read/interpret due to the large amount of information presented. For example, a number of conventional SPL meters use liquid crystal displays. Although liquid crystal displays are configurable to present a wide range of information, such displays are also difficult to read in direct or indirect sunlight and are therefore difficult to use in outdoor automotive competitions and are also difficult to use within a single automobile to monitor audio system SPL levels.
Ironically, the same features and complexity that contribute to the inadequacy of conventional SPL meters for use in automotive audio SPL competitions and for vehicle SPL monitoring also increase the cost of such conventional SPL meters. The high cost of conventional SPL meters further inhibits the use of SPL meters by SPL competitors in preparation for a competition, by individuals interested in monitoring sound pressure levels within their vehicles, and/or by individuals interested in conducting their own ad-hoc amateur SPL competitions without investing a significant amount of money for a conventional SPL meter that may likely be damaged by the intended use. Moreover, there are no commercially available self-contained SPL meters that are temporarily mountable within vehicles, such that acoustic competitions can be performed conveniently by temporarily mounting and removing an SPL meter from a plurality of vehicles.
Hence, a need remains for a cost effective, accurate and portable sound pressure level (SPL) meter that can be mounted within a vehicle to monitor interior sound pressure levels within a single vehicle and/or to measure and compare maximum sound pressure levels achieved within multiple vehicles in support of automobile audio system SPL competitions. Preferably, the SPL meter would be capable of being securely and unobtrusively mounted within a vehicle for temporary or prolonged use by individuals to monitor sound pressure levels in a single vehicle as well as capable of being quickly and easily mounted within competing SPL competition vehicles in a position that is consistent across competing vehicles. In addition, the SPL meter would be capable of withstanding prolonged and/or repeated exposure to high decibel levels and would withstand being stored and/or operated under varied operating environments including low/high humidity and low/high temperature conditions. Furthermore, the SPL meter should be easy to operate regardless of whether the SPL meter is used to monitor sound pressure levels in a single vehicle or used to conduct a SPL competition involving many contestants and should provide ergonomic viewing of measured results via a clear, intuitive display.